180 TENDRIL-BEARERS. Cuar. IV. 
these movement 
caused.* In the first place it may be remarked that the 
movement of nutation differs from that due toa touch, 
in so far that in some cases the two powers are acquired 
_by the same tendril at different periods of growth; 
and the sensitive part of the tendril does not seem 
capable of nutation. One of my chief reasons for doubt- 
ing whether the curvature from a touch is the result 
of growth, is the extraordinary rapidity of the move- 
ment. JI have seen‘the extremity of a tendril of 
Passiflora gracilis, after being touched, distinctly bent 
in 25 seconds, and often in 30 seconds; and so it is 
with the thicker tendril of Sicyos. It appears hardly 
credible that their outer surfaces could have actually 
grown in length, which implies a permanent modifica- 
tion of structure, in so short a time. The growth, 
moreover, on this view must be considerable, for if the 
touch has been at all rough the extremity is coiled 
in two or three minutes into a spire of several turns. 
When the extreme tip of the tendril of Echinocystis 
caught hold of a smooth stick, it coiled itself in a 
few hours (as described at p. 182) twice or thrice round 
* It occurred to me that the 
movement of nutation and that 
from a touch might be differently 
affected by anesthetics, in the 
same manner as Paul Bert has 
shown to be the case with the 
sleep-movements of Mimosa and 
those from a touch. I tried the 
common pea and Passiflora gra- 
“rie ether, 
cilis, but I succeeded only in ob- 
serving that both movements were 
unaffected by exposure for 13 hrs. 
to arather large dose of sulphu- 
In this respect they 
present a wonderful contrast with 
Drosera, owing no doubt to the 
presence of absorbent glands in 
the latter plant, 
